What are the main fixes to the problem of a firearm which fails to lock back on the last round fired from the magazine?

What benefit would refitting the barrel have in correcting this program?

jaguarxk120

February 7, 2012, 05:54 PM

It would be a great help if you told every one the Rifle involved.

Make, model, type of acton, caliber, size of magazine.

And why do you want to refit the barrel?

PetahW

February 7, 2012, 08:00 PM

[What are the main fixes to the problem of a firearm which fails to lock back on the last round fired from the magazine?]
Causes, not fixes:
A worn locking edge on a vertical magazine actuated slide lock.
A worn/broken stop latch.

[What benefit would refitting the barrel have in correcting this program? ] - None.

.

James K

February 7, 2012, 09:16 PM

The OP just said "firearm", which could include any gun with a magazine - pistol, rifle, or shotgun - including many that were never made to lock open on empty.

I think we need to wait for pictures or at least a better description of the "firearm."

Jim

dajowi

February 7, 2012, 11:57 PM

The firearm in question is a Springfield Armory EMP 9mm 1911 pistol. It fails to lock back the slide on the last round fired. It makes no difference who shoots it. It malfunctions with both 115 Gr. and 124 Gr. FMJ ammo. It fails with all three magazines which came with the gun. The first trip back to SA the barrel was refitted and the slide stop was tuned. They machined off some of the back of the slide stop. The gun continued to malfunction. It went back to S.A. and is in the process of being returned. They again, refitted the barrel and did extensive test firing.

So beside the original question of what good would refitting the barrel do to correct this program? If it continues when returned are their other possible fixes?

gyvel

February 8, 2012, 04:19 AM

I can't think of any other reason besides magazine followers that aren't hitting the hold open, unless the barrel link is causing a slight downward twist of the slide stop. (I am assuming that there is a barrel link and not a cam lock arrangement.) The only other thing, although far fetched, is that the recoil spring is not allowing the slide to travel back far enough for the slide stop to engage.

brickeyee

February 8, 2012, 12:32 PM

Check if the magazine follower is catching the slide stop since that is how the 'last shot lock' operates.

See if the follower is catching when you hand cycle the slide (good test with dummy rounds).
Look down into the rejection port as you cycle the slide by hand.

Q:Is it real easy to engage the slide stop manually?Smetimes a little detent is drilled in the slide stop,and it can be too much detent real easy.

Empty mag inserted,pull the slide full back,does it engage?

Weak mag spring?Try a new Wolfe +5%

dajowi

February 11, 2012, 02:50 PM

UPDATE: After a second trip to Springfield Armory for repair, (on their dime) the second "barrel refit" appears to have corrected the problem. Went to the range and shot 113 rounds of mixed 147 gr. fp, 115 gr. fmj and 115 gr. RNL. All worked perfectly with the exception that twice the slide failed to lock back on the 147 gr. FP. The OAL of the 147 Gr. cartridges are shorter than the other ammo I shot whether that had anything to do with it I don't know.

gyvel

February 13, 2012, 05:52 AM

A so-called "barrel refit" would make sense regarding my thoughts that the swinging link was exerting too much pressure on the slide stop.

The resulting friction/torsion when the barrel is swinging down out of engagement with the locking lugs in the slide would cause the slide stop to rotate down.

sarg1c

February 22, 2012, 08:38 AM

Check the lever spring, My Walther broke this very small spring and slide would not stay back on last round. I man. new spring, problem solved...

ScottRiqui

February 22, 2012, 08:53 AM

I had the same problem with my brand-new EMP .40 S&W. Eight mags, and none would lock the slide back reliably. I contacted SA, and they sent me a new slide stop pin with a different profile (I think they called it an "A-cut profile") that fixed the problem immediately and completely.

Glad they got yours taken care of as well!

Herr Walther

February 22, 2012, 08:53 AM

That little spring can get away from you too during a strip cleaning. I always have a few extra around.